epidemiologial study of bovine brucellosis in three selected agro-ecologies of central oromia in...
DESCRIPTION
Presented by Tujuba Jergefa Oncho at a Workshop: An Integrated Approach to Controlling Brucellosis in Africa, Addis Ababa, 29-31 January 2013TRANSCRIPT
Epidemiologial study of bovine brucellosis in three selected agro-ecologies of central Oromia in Ethiopia
Tujuba Jergefa Oncho
DVM,MVSc and Assistant Professor in Wollega University
Workshop: An Integrated Approach to Controlling Brucellosis in Africa, Addis
Ababa, 29-31 January 2013
Introduction
Bovine brucellosis is existing t in Ethiopia specially in extensive pastoral and in peri urban dairy farms in central highland.
High prevalence as high as 38.7%, 22%, is reported by Rashid,M.(1993) and
Sintaro,T.(1994) in cross breeds.
Background
Midium prevalence, 8.1%, is reported by Asfow,Y.(1998)in urban and peri urban dairy farms and 12.3% by OADB (1998).
Low prevalence 0.2 and 0.77 is reported by (Taddalle,2004) and 1.66 and 2.4 percent by (Ksshun, 2004) in cross and local breeds, respectively.
The status of the disease in smallholder dairy cattle in different Agro-ecology is not yet well assessed.
There are several un coordinated studies using different serological test procedures.
Study gaps
Current epidemiological picture of Brucellosis in Ethiopia.
Prevalence of Bovine brucellosis in Ethiopia.Determining potential risk factors and the
effect agro ecology on prevalence of brucellosis in Ethiopia.
Determining zoonotic significance of Brucellosis in farming households and consumers
Its economic burden in livestock production in Ethiopia
Sero- epidemiological study of Bovine brucellosis in central Ethiopia
3.Materials and methods
Study areasCentral Oromia/ Ethiopia Three districts
• Adami Tululu……lowland agro ecology• Lume= Modjo Midland…… agro ecology• Holota ……Highland agro-ecology
3.2. Study population.
All cattle population above 6 months age in the study areas were used as the study population.
Local breed Cross breed dairy cattle
3.3.Study design and methods
Cross-sectional Sero- Epidemiological study and
questionnaire survey
3.4. Sampling methodology
Sampling methodology One stage cluster sampling method Random selection of three Farmers’ Associations
from each of the three agro-ecologies and the main town of each of the three districts.
Random selection of 29 households (clusters) All animals under the management of the selected
households above six month of age were sampled.
Sample size
Sample size determination the actual cluster size at 95% CI ,5% absolute
precision and P = 12.3%%(OADB) is as given by the formula:
g = 1.962 (nVc+ Pexp(1-Pexp) ) nd2
where,g= number of clusters to be sampled,
Pexp =expected prevalence, d = desired absolute precision and Vc =between cluster variance (Thrusfield 1995).
Sample size cont…
Actually 1238 animals and 176 households were Included in the study 59 HHS 423 animals from lowland 58HHS 385 animals from mid highland 59HHS 430 animals from highland
Data collection
About 10ml blood was collected from jugular vein by clean vacutuner tubesThe collected blood was kept at room
temperature for clot retraction and serum separation
The separated serum was collected by pipette and stored at -20 oc until tested by RBPT and CFT
3.5.Materials used
Materials used for Rose Bengal Plate Test (RBPT) 1. Brucella Antigen for RBPT 2. Known Brucella positive Control sera 3. Known Brucella Negative control sera 3.Test serum 4.micropippete tips and epindorf tube 4.Enamel plate and Glass slide 5.Plastic applicator
Materials needed cont…
Materials needed for Complement Fixation Test (CFT)
1.Micro well plates (U-shaped), Multi channel and single channel micro pipets, pipet tips
2.Flasks and measuring cylinders3.Beam balance (Digital balance)4.Incubetor, water bath, deep freezer, Centrifuge5.Vernal buffer, Alsever solution,6. Complement, Hemolysin (Amboceptor), Control
Serra, Sheep RBC7 . CFT Antigen
4.Data recording and analysis
Microsoft Excel spread sheet was used for row data recording &management.
Intercooled stata 7.0 , spss & Win Episcope 2.0 soft wares were used as appropriate.
for data summary and analysis descriptive and analytical statistics of various dependant variables, stata 7.0( 2001) was used.
Chi square test and Fisher's exact t-tests were used to test Brucella Sero- prevalence with incriminated categorical risk factors.
Univarate and multiple logistic regression test were used to see the effect of potential risk factors on the prevalence of Bovine brucellosis
5.ResultTable 6.Overall individual animal seroprevalence of Bovine brucellosis in the three agro-
ecological zones
Number of seropositive animals (prevalence) Agro-ecology N
RBPT CFT
Lowland 423 24 (5.67%) 18 (4.26%) Mid-highland 385 10 (2.60%) 4 (1.04%) Highland 430 27 (6.26%) 15 (3.48%) Total 1238 61 (4.92%) 37 (2.99%)
N=number of animals tested
Overall herd sero prevalence
Table 8: Overall herd seroprevalence of bovine brucellosis in the three agro-ecological zones
Number of seropositive households(prevalence) Agro-ecology NF RBPT CFT
Lowland 59 14(23.7% 10 (17%) Mid-highland 58 6(10.3%) 3 (5.17%) Highland 59 8 (13.6%) 11 (18.64%) Total 176 28 (16 %) 24 (13.64%)
NF=number of farms tested
.Table 9.Factors affecting the overall individual animal seroprevalence in the study areas
(univariate logistic regression analysis)
Risk factors Group N Number positive
(prevalence) 95% CI P-value OR
Indigenous 892 20 (2.24%) 1.16-4.26 0.017 2.22 Breed Crossbred 346 17 (4.91%)
0.5-3 years 412 17 (4.12%) 0.36-1.11 0.115 - 3-10 years 729 18 (2.47%)
Age group
> 10 years 97 2 (2.06%) 1-6 296 16 (5.41%) 0.72-2.39 0.373 -
7-16 537 9 (1.68%)
Herd size
>16 405 12 (2.96%) Intensive 266 13 (4.88%) 1.00-2.03 0.046 1.43 Semi-intensive 70 2 (2.86%)
Management system
Extensive 902 22 (2.43%) Lowland 423 18 (4.26%) 0.59-1.30 0.519 - Mid-highland 385 4(1.04%)
Agro-ecology
Highland 430 15(3.49%) Natural 894 20(2.2%) 0.87-1.86 0.213 Artificial 116 11(9.5%)
Mating method
Both 228 6(2.6%) Regional market 891 20(2.24%) 0.91-1.70 0.176 - Village breeders 236 13(5.51%) Government farms 6 1(16.67%)
Source of replacement stock
Urban dairy farms 105 3(2.86%)
.
Table 10. Factors affecting individual animal seroprevalence in the lowland areas (univariate logistic regression analysis)
Risk factors Group N Number positive (prevalence)
95% CI P-value OR
Indigenous 336 9(2.7%) 1.61-10.91 0.015 4.19 Breed Crossbred 87 9(10.3%)
0.5-3 years 143 7(4.9%) 0.35-1.66 0.498 - 3-10 years 237 10(4.2%)
Age group
> 10 years 43 1(2.3%) 1-6 98 10(10.2) 0.22-0.77 0.006 0.41
7-16 143 4(2.8%)
Herd size
>16 182 4(2.2%) Intensive 87 9(10.3) 1.27-3.30 0.003 2.05 Management
system Extensive 336 9(2.7%) Natural 335 9(2.7%) 1.59-10.74 0.004 Mating method Artificial 88 9(10.3%)
Source of replacement stock
Regional market 335 9(2.7%) 1.59-10.74 0.004 -
.Table 11. Factors affecting individual animal seroprevalence in the mid-altitude areas
(univariate logistic regression analysis)
Risk factors Group N Number positive (prevalence)
95% CI P-value OR
Indigenous 280 1(0.4%) 0.97-9.86 0.056 - Breed Crossbred 105 3(2.9%)
0.5-3 years 104 2(1.9%) 0.06-2.28 0.279 - 3-10 years 253 2(0.8%)
Age group
> 10 years 28 0 1-6 112 3(2.7%) 0.02-1.35 0.092 -
7-16 198 1(0.5%)
Herd size
>16 75 0 Intensive 105 3(2.9%) 0.92-8.93 0.070 - Management
system Extensive 280 1(0.4%)
Natural 283 1(0.4) 0.94-9.12 0.065 - Mating method
Artificial 102 3(2.9%)
Regional market 280 1(0.4%) 0.95-4.30 0.070 - Source of replacement stock Urban dairy farm 105 3(2.9%)
.Table 12. Factors affecting individual animal seroprevalence in the highland areas
(Univariate Logistic Regression Analysis)
Risk factors Group N Number positive (prevalence)
95% CI P-value OR
Indigenous 276 10(3.6%) 0.48-2.23 0.937 - Breed
Crossbred 154 5(3.2%)
0.5-3 years 165 8(4.8%) 0.25-1.59 0.334 -
3-10 years 239 6(2.5%)
Age group
> 10 years 26 1(3.8%)
1-6 86 3(3.5%) 0.70-3.13 0.306 -
7-16 196 4(2%)
Herd size
>16 148 8(5.4%) Intensive 286 12(4.2%) 0.0.25-1.41 0.232 -
Semi-intensive 70 2(2.9%)
Management system
Extensive 74 1(1.4%)
Natural 276 10(3.6%) 0.46-1.56 0.608 -
Artificial 28 2(7.1%)
Mating method
Both 126 3(2.4%)
Regional market 276 10(3.6%) 0.42-2.99 0.830 -
Village breeders 148 4(2.7%)
Source of replacement stock
Government farm 6 1(16.7%)
Questionnaire survey result
. Association of Bovine brucellosis sero-prevalence with the cause of culling Table 14. Brucellosis sero-prevalence Vis a’ Vis reason of culling
CFT reason of culling
NHHs Interview) Number of animals tested
Number(%) positive animals
Number (%) positive HHs
Sick animal 2 12 0(%) 0(0%) Infertility 60 430 9(21%) 6(10%) Poor production
6 42 2(3%) 2(33.34%)
Overstock 55 385 23(6%) 14(25%) Miscellaneous and urgent cash need
53 368 3(0.8%) 2(4%)
Total 176 1237 37 24 NHHS = Number of households, HHS = Households OR = 1.45, p-value = 0.013
.
.
Table 14: Summary of farmers attributes on cattle management in the study areas Educational back ground of the farmers
Indigenous (LocalBreed) holders ( n=89)
Dairy Cross Breed Holders ( n=87 )
Total
Traditional (from the family)
71/89(81%) 59/87 (67.82% ) 130/176(74.71%)
Agricultural Extension
16/89(18%) 21/87 (24.14% ) 37/176(21.26%)
Formal Agricultural Training school
0
7/87 (8.05% ) 7/176(4.02%)
Type of Matting used Natural
89/89
13/87(14.94% )
100/176(57.47%)
Artificial
0 20/87 (22.98% )
20/176(11.44%)
Natural + Artificial
0 54/87 (62.10% )
56/176(31.03%)
Knowledge of brucellosis and abortion causing disease
Yes
7/89 11/87 (12.64% )
21/176(12%)
No
82/89(94.25%)
76/87 (87.36% ) 158/176(88%)
Method of disposal of aborted materials and after birth Proper Improper
7/89(5.74%) 82/89(94.25%)
67/87 ( 77.01% ) 20/87 (22.99% )
72/176(41.37%) 104/176(59.63%)
Presence of separate parturition pen
11/89(12.64%)
15/87(17.24%) 26/176(14.94%)
Regular cleaning of animal premises.
49/89(56.32%)
57/87(65.52%)
106/176(60.91%)
.
.
Table 14: Summary of farmers attributes on cattle management in the study areas Educational back ground of the farmers
Indigenous(Traditional Local Breed )Holders ( n=89)
Dairy Cross Breed Holders ( n=87 )
Total
Traditional (from the family)
71/89(81%) 59/87 (67.82% ) 130/176(74.71%)
Agricultural Extension
16/89(18%) 21/87 (24.14% ) 37/176(21.26%)
Formal Agricultural Training school
0 7/87 (8.05% ) 7/176(4.02%)
Type of Matting used Natural
89/89
13/87(14.94% )
100/176(57.47%)
Artificial
0 20/87 (22.98% )
20/176(11.44%)
Natural + Artificial
0 54/87 (62.10% )
56/176(31.03%)
Knowledge of brucellosis and abortion causing disease
.
.
..
Source of Replacement Stock
Regional Market
89/89(100%)
62/87 (71.26% )
149/176(84.65%)
Village Breeders 0 17/87 (19.54% ) 17/176(9.77%) Government Farms 0
8/87 (9.19% )
8/176(4.5%)
Urban Dairy Farms 0 40/87(45.97%) 40/176(22.77%)
Reasons of culling
Disease
0 4/87 ( 4.60% ) 4/176(2.30%)
Infertility 33/89(37.93%) 31/87 (35.63%) 64/176(36.78%)
Poor production
0 14/87(16.09 ) 14/176(8.05%)
Other reasons (Old age, over stock and urgent cash needs )
26/89(29.88%) 38/87 (43.67% )
64/176(36.78%)
Combination of the above reasons
28/89(32.18%) 21 (24.14%) 49/176(28.16%)
n= number of households
Prevalence of reproductive diseases
.
Table 15: Summary of the proportion of productive cows by physiological status vis-à-vis abortion, stillbirth, and retained fetal membrane, prevalence Physiological status Dairy cross breed Traditional local breed Total Lactating and pregnant cows
197/347 (57.06% ) 217/890 ( 24.38% ) 414/1237 (33.47% )
Dry pregnant cows 8/347 ( 2.31% ) 30/890 (3.37% ) 38/1237 (3.07 %) Total 205 247 452 History of abortion 9/205 (4.39% ) 6 /247 (2.43% ) 15/452 (3.32% )
History of stillbirth 6/205 ( 2.92% ) 2/247 ( 0.81% ) 8/452 ( 1.77% ) History of retained fetal membrane
9/205 ( 4.39% ) 3/247 (1.21% ) 12/452 (2.65% )
zoonotic importance
.Table16. Association of Bovine brucellosis sero prevalence with prolonged fever in the households (families surveyed) Existence of prolonged fever in the family
NHHS( Interview) CFT NHHS with no sero positive animals
NHHS with sero positive animals
Yes 41 39 2(5%) No 136 131 4 (3%) Total 176 170 5(2.8%) NHHS = Number of households, HHS = Households OR = 1.30, p-value = 0.492
Conclussions
The overall sero-prevalence of Bovine brucellosis in the study area is low
Highest in the lowland and the highland the lowest prevalence was recorded in the mid highland agro ecology.
Conclussions… cont
• Breed and management were found to be the most important risk factor associated with Bovine brucellosis in the study area.
Conclssion…contd
• Zoonotic importance of Bovine brucellosis was appreciated through association of prolonged fever in the animal breeding households and presence of sero positive animals under their management.
Conclussions… contd
• Awareness of the households(farmers)on Brucellosis and abortion causing diseases was
low; management of the animals, cleaning of the housings and the surroundings as well as the method of disposal of aborted materials and after birth is poor; hence Brucellosis can easily be transmitted within the herd or to the other healthy herds in the area.
Recommendation
Comprehensive and coordinated epidemiological study throughout Ethiopia is needed to formulate appropriate policy to control the disease.
Regular testing of animals specially the breeding animals before transporting them to other areas.
Test and culling of positive animalsAwareness creation for the stakeholders about
the severity of the disease both on animal production and human health.